From d903e34cacd18157a2a60e7b112eb05af2766266 Mon Sep 17 00:00:00 2001
From: raeno <just.raeno@gmail.com>
Date: Wed, 12 Dec 2018 22:37:00 +0300
Subject: [PATCH] Add opengraph/twitter_card:summary support. Add config to
 toggle on/off specific metadata

---
 config/config.exs                             |  4 ++
 lib/pleroma/web/ostatus/ostatus.ex            | 58 +++++++++++++++++--
 lib/pleroma/web/ostatus/ostatus_controller.ex |  6 +-
 3 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/config/config.exs b/config/config.exs
index 1401b0a3d..ad4b79f54 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -171,6 +171,10 @@
   ip: {0, 0, 0, 0},
   port: 9999
 
+config :pleroma, :metadata,
+  oembed: false,
+  opengraph: true
+
 config :pleroma, :suggestions,
   enabled: false,
   third_party_engine:
diff --git a/lib/pleroma/web/ostatus/ostatus.ex b/lib/pleroma/web/ostatus/ostatus.ex
index 0f6756d16..73cdd3837 100644
--- a/lib/pleroma/web/ostatus/ostatus.ex
+++ b/lib/pleroma/web/ostatus/ostatus.ex
@@ -5,11 +5,12 @@ defmodule Pleroma.Web.OStatus do
   import Pleroma.Web.XML
   require Logger
 
-  alias Pleroma.{Repo, User, Web, Object, Activity}
+  alias Pleroma.{Repo, User, Web, Object, Activity, Formatter}
   alias Pleroma.Web.ActivityPub.ActivityPub
-  alias Pleroma.Web.{WebFinger, Websub}
+  alias Pleroma.Web.{WebFinger, Websub, MediaProxy}
   alias Pleroma.Web.OStatus.{FollowHandler, UnfollowHandler, NoteHandler, DeleteHandler}
   alias Pleroma.Web.ActivityPub.Transmogrifier
+  alias Phoenix.HTML
 
   def is_representable?(%Activity{data: data}) do
     object = Object.normalize(data["object"])
@@ -26,14 +27,59 @@ def is_representable?(%Activity{data: data}) do
     end
   end
 
-  def metadata(url), do: oembed_links(url)
+  def metadata(activity, user, url) do
+    Enum.concat([
+      if(meta_enabled?(:opengraph), do: opengraph_tags(activity, user), else: []),
+      if(meta_enabled?(:oembed), do: oembed_links(url), else: [])
+    ])
+    |> Enum.map(&to_tag/1)
+    |> Enum.map(&HTML.safe_to_string/1)
+    |> Enum.join("\n")
+  end
+
+  def meta_enabled?(type) do
+    config = Pleroma.Config.get(:metadata, [])
+    Keyword.get(config, type, false)
+  end
+
+  def to_tag(data) do
+    with {name, attrs, _content = []} <- data do
+      HTML.Tag.tag(name, attrs)
+    else
+      {name, attrs, content} ->
+        HTML.Tag.content_tag(name, content, attrs)
+
+      _ ->
+        raise ArgumentError, message: "make_tag invalid args"
+    end
+  end
 
   def oembed_links(url) do
     Enum.map(["xml", "json"], fn format ->
-      href = oembed_path(url, format)
-      "<link rel=\"alternate\" type=\"application/#{format}+oembed\" href=\"#{href}\">"
+      href = HTML.raw(oembed_path(url, format))
+      { :link, [ type: ["application/#{format}+oembed"], href: href, rel: 'alternate'], [] }
     end)
-    |> Enum.join("\r\n")
+  end
+
+  def opengraph_tags(activity, user) do
+    with image = User.avatar_url(user) |> MediaProxy.url(),
+         truncated_content = Formatter.truncate(activity.data["object"]["content"]),
+         domain = Pleroma.Config.get([:instance, :domain], "UNKNOWN_DOMAIN") do
+      [
+        {:meta,
+          [
+            property: "og:title",
+            content: "#{user.name} (@#{user.nickname}@#{domain}) post ##{activity.id}"
+          ], []},
+        {:meta, [property: "og:url", content: activity.data["id"]], []},
+        {:meta, [property: "og:description", content: truncated_content],
+          []},
+        {:meta, [property: "og:image", content: image], []},
+        {:meta, [property: "og:image:width", content: 120], []},
+        {:meta, [property: "og:image:height", content: 120], []},
+        {:meta, [property: "twitter:card", content: "summary"], []}
+      ]
+    end
   end
 
   def feed_path(user) do
diff --git a/lib/pleroma/web/ostatus/ostatus_controller.ex b/lib/pleroma/web/ostatus/ostatus_controller.ex
index 27ec24f57..bfc36c0c4 100644
--- a/lib/pleroma/web/ostatus/ostatus_controller.ex
+++ b/lib/pleroma/web/ostatus/ostatus_controller.ex
@@ -134,7 +134,7 @@ def notice(conn, %{"id" => id}) do
          %User{} = user <- User.get_cached_by_ap_id(activity.data["actor"]) do
       case format = get_format(conn) do
         "html" ->
-          serve_static_with_meta(conn, activity)
+          serve_static_with_meta(conn, activity, user)
 
         _ ->
           represent_activity(conn, format, activity, user)
@@ -151,9 +151,9 @@ def notice(conn, %{"id" => id}) do
     end
   end
 
-  defp serve_static_with_meta(conn, activity) do
+  defp serve_static_with_meta(conn, activity, user) do
     {:ok, index_content } = File.read(Application.app_dir(:pleroma, "priv/static/index.html"))
-    links = OStatus.metadata(request_url(conn))
+    links = OStatus.metadata(activity, user, request_url(conn))
     response = String.replace(index_content, "<!--server-generated-meta-->", links)
     conn
     |> put_resp_content_type("text/html")